The invention is directed to a converter with a container adapted to receive molten metal and with a measurement device for optical temperature determination of the molten metal, and a method for temperature determination in such container.
In steel production, pig iron is converted into steel predominantly in an oxygen blow converter. To this end, typically 150 tons to 400 tons of liquid pig iron are filled into a large crucible-shaped container (converter vessel) and converted into crude steel by blowing in and/or blowing through large quantities of oxygen. The temperature of the metal bath increases due to the combustion of the undesirable pig iron components.
The important target value for a control process is the temperature of the steel bath at the end of the converter process. For measuring the temperature, the converter process is typically interrupted and the temperature is measured manually. For example, measurement rods with thermocouples attached at one end are inserted into the molten metal.
The time required for the temperature measurement and the resulting corrective measures make it difficult to control the process and the process flow. Measures are therefore taken to measure the temperature continuously in situ during the converter process, which significantly improves the process flow and also markedly increases the efficiency of the steel production.
For example, it is known from practical applications to continuously measure the temperature in situ by conducting a pyrometric analysis of the electromagnetic radiation emitted from the steel bath. For example, the surface of the steel bath is monitored. However, this method produces unacceptable measurement uncertainties due to a severely variable emission from the heterogeneous and vigorously moving bath level. Providing inserts, such as windows, in the fireproof brick wall of the converter has also been considered. However, windows have certain disadvantages due to the optical degradation caused by the high temperatures which can reach 1800° C. Access ports provided in the fireproof bricks are under severe mechanical stress due to settlement processes which deform the mostly tube-shaped access ports to the melt to such a degree so as to obstruct optical access to the steel bath along the line of sight.